.changeset/dull-ads-shake.md src/next/mcp-api-handler.ts

Author: quuu

.changeset/dull-ads-shake.md

@@ -0,0 +1,5 @@
+---
+"@vercel/mcp-adapter": patch
+---
+
+Fix allowing both async and non async handlers

src/next/mcp-api-handler.ts

@@ -152,8 +152,8 @@ export function calculateEndpoints({
     sseEndpoint: fullSseEndpoint,
     sseMessageEndpoint: fullSseMessageEndpoint,
   } = basePath != null
-    ? deriveEndpointsFromBasePath(basePath)
-    : {
+      ? deriveEndpointsFromBasePath(basePath)
+      : {
         streamableHttpEndpoint,
         sseEndpoint,
         sseMessageEndpoint,
@@ -203,7 +203,9 @@ async function initializeRedis({
 }
 
 export function initializeMcpApiHandler(
-  initializeServer: (server: McpServer) => Promise<void>,
+  initializeServer:
+    | ((server: McpServer) => Promise<void>)
+    | ((server: McpServer) => void),
   serverOptions: ServerOptions = {},
   config: Config = {
     redisUrl: process.env.REDIS_URL || process.env.KV_URL,
@@ -633,7 +635,7 @@ function createFakeIncomingMessage(
 
   // Create a readable stream that will be used as the base for IncomingMessage
   const readable = new Readable();
-  readable._read = (): void => {}; // Required implementation
+  readable._read = (): void => { }; // Required implementation
 
   // Add the body content if provided
   if (body) {